Early in my career, I was quick to point out the 90%. This won't work. That won't scale. This is not even wrong. But anyone can identify the 90%. Even if you believe everything is crap, you'd still be right 9 out of 10 times. Stop wasting time dunking on the 90% (but there's still no time to read bad books).

The biggest challenge is figuring out the 10% that could go right. That's a lot harder and more impressive. It means the payoff is higher for betting on what could go right, not what could go wrong. For the options traders: buy calls, not puts (especially in this market).

The 90% rule is known as Sturgeon's Law. Theodore Sturgeon was a science fiction critic who was responding to the criticism that "90% of science fiction was crap". Sturgeon noted that 90% of pretty much anything was crap. Some fun related ideas include the 90-90-rule from Tom Cargill at Bell Labs:

The first 90% of code accounts for the first 90% of the development time.
The remaining 10% of the code accounts for the other 90% of development time.

The Pareto Principle (the "80/20" rule):

roughly 80% of the consequences come from 20% of the causes

And some more humorous derivatives: